The effect of Coulomb interaction on Levy source parameters

Abstract

Femtoscopy plays an important role in the study of heavy-ion collisions and particle sources generated within them. In both experimental measurements and theoretical models, a Lévy distribution is used to describe the shape of the source, as the Gaussian distribution has proven to be inaccurate based on experimental observations. Despite this, there are still discrepancies between experimental data and the results of theoretical models. One reason may be that these theoretical models either approximate the Coulomb interaction poorly or omit it entirely. In our research, we focused on how the Coulomb effect influences the stability index $α$ value of the Lévy distribution. For this, we used a custom-developed simulation framework written in C++ and Python. The C++ module integrates the equations of motion for relativistic pions using the Leapfrog algorithm, while the Python post-processing script generates the two-particle spatial source function from the phase-space coordinates. We investigate the ratio and slope of the generated and pair-source fitted $α$ as a function of the number of particles, fitting range, and the initial source size and density.